Download - Faint Red Galaxies
Faint Red Galaxies
Evolved stars at High Redshift
May 28, 2003
P. J. McCarthy
UCSC
Carnegie Observatories
Distant Galaxy Studies in the 20th Century
• Focused on faint blue galaxies
• Samples UV bright populations
• Traces heavy element production
• Global census of conversion of gas into stars
Evolution of UV luminosity density
Madau et al
Steidel et al 99
Faint Galaxies in the Near Infrared
• Sensitive to assembly of galaxies via mergers
• Near-IR offers a window on mass evolution
• Dust not (as) important
Build-up of stellar mass over cosmic time
Near-IR luminosity provides proxy for
stellar mass
Near IR-surveys are technically challenging
Optical and near-IR Detectors
Large formats: 2k x 4k
3 edge buttable
100 Mpixel FPAs common
Cheap - $ 0.01 per pixel
2k x 2k maximum Non-buttable
Expensive
$ 0.13 per pixel !
Challenges facing Deep near-IR Surveys
• Detectors small and Expensive
• Cryogenic Optics & baffles required
• Sky 3 orders of magnitude brighter!
• Can’t observe when the moon is down!
Earliest IR Surveys – New Red population
Elston, Rieke & Rieke 1989 10 sq .arcminutes
Hu & Ridgeway 1992
100 sq. arcminutes
Some EROs are Sub-mm sources
Dey et al. 1999
Smail et al. 1999
Two Red populations?
Moderately red, high surface density on sky
Z ~ 1 early types
Extreme red colors, very rare
Z > 1 Starbursts
Las Campanas IR Survey
McCarthy, Persson, Martini, Koviak (OCIW)
Chen (MIT), Marzke(SFSU), Carlberg, Abraham(UT)
Ellis (Caltech), Firth, McMahon, Lahav (IoA)
PHASE I: A Carnegie-Cambridge-Toronto Collaboration
PHASE II: A Diversified Conglomerate
• Galaxy Assembly in the 1 < z < 2 Epoch• Space density of massive galaxies• Stellar evolution in early type galaxies• Evolution of 3-D Clustering• Growth of massive galaxies and structure
GOALS
Why Select in the near-IR?
•Selects on basis of population with high
M/L
•Optical-IR color indices excellent for foreground rejection
•That where the light is!
V I H KZ = 1.5
Approach
• Multi-color optical & near-IR imaging survey
• Depths keyed to z = 2 elliptical: Ks ~ 21 !
• Photometric redshifts
• Six fields around the celestial sphere
• 1 square degree
Color-Mag Diagrams Color-Redshift Diagrams
Number Counts Color-Color Diagrams
Luminosity Functions Angular Clustering
Morphologies Spectroscopy
• Phase I: 1 square degree to H = 20.5 + VRI • Phase II: 1 square degree to K = 20.8 + BVRIz’JH • VRIH survey completed in spring 2001• 0.75 square degrees J & K in hand• ~10,000 K-selected objects• ~70,000 photometric redshifts• ~ 350 spectroscopic redshifts
Reality Intrudes!
CIRSI + LCO Wide Field IR Camera
du Pont 2.5m telescope 4 1024 x 1024 arrays
cryogenic Offner relay 16 channel electronics
4 1024x1024 detectors – 90% gaps
4 pointings – 16 1024 x 1024 images
4 pointings – 16 1024 x 1024 images
4 pointings – 16 1024 x 1024 images
13’ x 13’ mosaic – 3 hour exposure
100,000
1024 x 1024
Frames - 30 seconds each
Red Galaxies are Abundant
V,I,K
80”
Photometric Redshifts• 8 color photometery BVRIz’JHKs
• 6 Galaxy templates
• 1 AGN, 128 stellar templates
Best fit template and redshift
Likelihood function
See Koo 1985
Connolly et al 1995,1997
Photometric Redshifts from LCIR
Chen et al 2002
Photometric Redshifts from LCIR
Recent update
GMOS redshifts
Basic Phenomenology:
Sky density, Space Density, Luminosity & Color Evolution
IR to Optical Color Selection
I-K > 4
Rejects z < 1
Foreground & late types at all redshifts
IR to Optical Color Selection
I-K > 4
Rejects z < 1
Foreground & late types at all redshifts
Color-Magnitude Diagram
Stars
0.0 < z < 1.0
1.0 < z < 1.5
1.5 < z < 2.0
2700 sq. arcmin
Classical Star Counts
Classical Star Counts
Number-Magnitude Relations
I-K > 4.0
I-K > 4.5
I-K > 5.0
Number-Magnitude Relations
I-K > 4.0
I-K > 4.5
I-K > 5.0
Gardner et al K-band LF
UV & Optical Color DiagnosticsV I H KZ = 1.5
Optical to IR color sensitive to old
population I-K
Rest-frame UV slope sensitive to
recent star formation
V-I
Color-Color Diagrams
• Stars form distinct sequence
K < 17.5
Color-Color Diagrams
• Stars form distinct sequence
K < 18.5
Color-Color Diagrams
• Stars form distinct sequence
• Z > 1 galaxies appear at K ~ 19
K < 19.5
Color-Color Diagrams
• Stars form distinct sequence
• Z > 1 galaxies appear at K ~ 19
• Z > 1.5 galaxies at K ~ 20
K < 20.8
Color-Color Diagrams
• Stars form distinct sequence
• Z > 1 galaxies appear at K ~ 19
• Z > 1.5 galaxies at K ~ 20
• Reddest galaxies follow minimal evolution track
K < 20.8
Evolving Luminosity Functions
Chen et al. 2002
Redshift errors must be explicitly
treated!
Luminosity functions
from photometric
redshifts
Evolving Luminosity Functions• LFs derived from photo-
z’s with modified likelihood approach
• LF at intermediate z agrees well with CNOC2
• Very little apparent evolution in L* to z ~ 1.2
Chen et al. 2002
R-band Luminosity Density
Rest-Frame R-band Luminosity density
little or no evolution to z ~ 1.2
Clustering:
A proxy for merging
Tags populations at high and low redshift
Angular vs. 3-D Clustering
Clustering of Red Galaxies
Angular Clustering
Clustering amplitude of red galaxies is 20 x that
of the full field
Angular Clustering
= 12”
I – K > 4
= 1”
All K < 20.5
Angular Clustering
Clustering amplitude higher for redder colors and brighter magnitudes.
= 30”
K ~ 18 & I-K > 5
n(z) required for r_0
Inversion of to r0
All I-K K > 19 <z> 0.7
I-K > 4 19 < K < 20 <z> 1.0
I-K > 4 18 < K < 19 <z> 1.0
’’ I-K > 5 18 < K < 20 <z> 1.2
Generalized Limber equation:
n(z) for I-K selected subsamples
Inversion of to r0
All I-K K > 19 <z> 0.7 5 h-1Mpc
I-K > 4 19 < K < 20 <z> 1.0 9
I-K > 4 18 < K < 19 <z> 1.0 9
’’ I-K > 5 18 < K < 20 <z> 1.2 10
Generalized Limber equation:
Evolution and Color Dependence
Red color selection or E morphological
selection
Blue color selection or late
type morphological
selection
LCRS CNOC2 CFRS CFGRS LBG
Evolution and Color Dependence
Kauffmann et al 99
Early types
Star forming galaxies
LCRS CNOC2 CFRS CFGRS LBG
Morphology:
What type of Galaxy are we talking about after all?
E/S0
Template
Match
Giavalisco
et al
Cycle 11
Treasury
Program
10/5/02 public release
91 objects
Giavalisco
et al
Cycle 11
Treasury
Program
10/5/02 public release
Sab/Sbc
Template
Match
Giavalisco
et al
Cycle 11
Treasury
Program
10/5/02 public release
54 objects
E/S0
Template
Match
Giavalisco
et al
Cycle 11
Treasury
Program
10/5/02 public release
Sab/Sbc
Template
Match
Morphologies of Red Galaxies4.0 < I – K < 4.5 <z> = 1.0
Template type 1 (E/S0)
85% Compact 10% Disks 5% Diffuse
Template type 2 (Sab/Sbc)
60% Compact 35% Disks 5% Diffuse
Template type 1 (E/S0)
60% Compact 25% Disks 15% Diffuse
Template type 2 (Sab/Sbc)
40% Compact 30% Disks 30% Diffuse
4.5 < I – K < 5.0 <z> = 1.2
See Stiavelli
& Treu 1999
NICMOS results
See
Yan & Thompson 2002
WFPC2 results
Spectroscopy:
Real redshifts and Spectral Diagnostics
Conventional Slit Spectroscopy
• Sky subtraction is primary limitation– Slit irregularities– Flat-field errors– Residual Fringing– Geometric distortions– Low slit density on sky
• Beam switching ?– Variable sky spectrum– Read noise penalty– High read-out overhead
• The solution: ‘nod & shuffle’Glazebrook &
Bland-Hawthorn 99
Sky cancellation: ‘nod and shuffle’Storage of ‘sky’ image next to object image via ‘charge shuffling’Zero extra noise introduced, rapid switching (60s)
A
B
AB
Typically A=60s/15 cy: 1800s exposure10 subtraction
GMOS N&S Sky residualsSUMMED along long slit (1.8 arcmin)
Raw Sky/20
Subtracted sky
(i.e. ~10 level is enough for 200,000 sec pointed obs.)
Cycle:A=60sB=60s
+ 25s o/head
Gemini + GMOS
GMOS spectrographGemini
GMOSLRISLDSS1
GMOS on Gemini North
5’ x 5’ FOV R ~ 800
GDDS Spectra77 objects 40,000 secs
[OII] Redshifts from GDDS
23.7 < I(AB) < 24.2
Absorption Line Spectra
I = 24.0
Z = 1.67
I = 23.7
Z = 1.56
I = 24.2
Z = 1.39
Rest Wavelength
Interstellar Matter at z = 1.5
Red: Local Star burst composite (Tremonti et al.)
Black: GDDS z = 1.5 I ~ 24.5 I-K < 3 composite
Interstellar Matter at z = 1.5
Interstellar Matter at z = 1.5
Gas Rich!
DLAs
Savaglio et al. 2003
K + A Galaxies
Only 1 in
10,000 galaxies in LCRS
have similar EWs
K + A Galaxies
>45% burst by mass with 500My age
~5% of red
galaxies are in this
class!
The Reddest Galaxies
The Reddest Galaxies
The Reddest Galaxies
Glazebrook et al in prep
Color Evolution
Photometric Redshifts Spectroscopic Redshifts
Color Evolution
Redshift desert is nearly gone……
Conclusions• Counts: little density evolution to z ~ 1.2• LFs: R-band Luminosity density declines by < x
2 to z ~ 1.5• UV colors: wide range of star formation levels• Clustering: Strong clustering consistent with
local E population• Morphologies: Predominantly early types• Spectroscopy: Old & Intermediate age
populations
The Progenitors of Early Type Galaxies
Conclusions
Population of massive field early types largely unevolved since z ~ 1.5
The Future
ACS imaging of the GDDS Fields
IMACS with its 27’ x 27’ and Nod & Shuffle with
> 1000 slits per mask: Large Scale Structure at z ~ 1.5